There is a flip chip technique as one of techniques for mounting semiconductor chips. With the flip chip technique, protrusive electrodes (bumps) are formed on the surface of the semiconductor chip, and those protrusive electrodes are directly connected to electrode pads on a substrate.
In the flip chip packaging, stresses generated due to the difference in thermal expansion coefficient between a semiconductor chip 30 and a substrate 29 are concentrated at a connecting portion 33 between them. To prevent the connecting portion 33 from being broken by the concentrated stresses, a resin 34 is filled in a gap between the semiconductor chip 30 and the substrate 29 with intent to reinforce the connecting portion 33. Such a process is called “underfilling” (see FIG. 6).
The underfilling process is performed by applying the liquid resin 34 along an outer periphery of the semiconductor chip 30 such that the resin 34 is filled into the gap between the semiconductor chip 30 and the substrate 29 by capillary action, and then heating the resin 34 in an oven, for example, to thereby harden the resin 34.
With the underfilling, a corner portion 35 made of the liquid resin 34 is formed in an edge portion demarcated by a side surface of the semiconductor chip 30 and the substrate 29. Such a corner portion is called a “fillet” (see FIG. 7). When the fillet 35 is not formed uniformly, the following problems, for example, arise. Air may enter the gap through a portion where the fillet 35 is relatively small, thus causing entrapment of air bubbles. The resin 34 may protrude over to an application prohibited region around the application target chip 30. The semiconductor chip 30 may be damaged when the resin 34 is heated to be hardened. Accordingly, the fillet 35 is required to be uniformly formed at a certain width (denoted by 36) and a certain height (denoted by 37).
Techniques for uniformly forming the fillet are proposed (disclosed) in Patent Document 1 and Patent Document 2.
In more detail, Patent Document 1 discloses a method for manufacturing a semiconductor package having a structure that a resin is filled in a gap between a semiconductor chip and a substrate mounted on the semiconductor chip, wherein a speed of a nozzle for supplying the resin is adjusted such that the resin supplied along one side of the semiconductor chip is supplied to a central portion of the semiconductor chip in larger amount than to an end portion of the semiconductor chip.
Also, Patent Document 2 discloses a method of moving a nozzle around a semiconductor chip that is face-down mounted to a wiring board, and filling an underfill material into a gap between the wiring board and the semiconductor chip by continuously supplying the underfill material from the nozzle, wherein a nozzle moving path is made up of a linear path positioned within a region between a pair of segments, which are drawn from both ends of a side of the semiconductor chip perpendicularly to the side, and a direction change path along which the nozzle moving path is changed to connect two linear paths adjacent to each other, the direction change path being continued to the linear path, and wherein the nozzle is moved at a lower speed in at least a portion of the linear path than in the direction change path.